Richardson opted out of the tournament to be with his wife for the birth of his first child.
"We're thrilled to welcome Adam Zampa in RCB colours. He replaces Kane Richardson. Let's #PlayBold Adam Zampa." RCB tweeted on Monday night.
"The RCB family is excited for Kane and his wife who are expecting the birth of their first child and respect his decision to pull out of the tournament," it added.
Zampa joins the likes of Yuzvendra Chahal, Washington Sundar, Moeen Ali and Pawan Negi, strengthening the team's spin attack.
"We are disappointed to not have Kane's skills with us this IPL, as he was certainly on top of his game," RCB team director Mike Hesson said.
"However, once we found out Kane and Nyki's baby was due during the IPL, it's an exciting time, and we were fully supportive of Kane wanting to be at the birth of their first child.
Hesson felt Zampa also gives the side "extra options if conditions suit spin as expected during the tournament."
This will be Zampa's second stint in the IPL as he earlier played for the Rising Pune Supergiant.
The 28-year-old went unsold at the auction last year while Richardson was bought for Rs 4 crore by RCB.
Both Richardson and Zampa are currently in England as part of Australia's squad for the white-ball tour.
The two teams are slated to play three T20Is and as many ODIs between September 4-16.
The 13th edition of IPL was shifted out of India due to the COVID-19 pandemic.
Let the Truth be known. If you read VB and like VB, please be a VB Supporter and Help us deliver the Truth to one and all.
Srinagar (PTI): Property worth Rs 1 crore belonging to a notorious drug peddler was on Saturday attached in Jammu and Kashmir's Srinagar, police said.
A double-storey house on eight marlas of land situated at Wantpora Eidgah, belonging to Basit Bilal Dar, a notorious drug peddler, valued at approximately Rs 1 crore, a police spokesperson said.
He said Dar is involved in two cases registered under various sections of the NDPS Act.
During investigation, it was established that the accused had acquired the said property through illicit proceeds generated from drug trafficking activities, the spokesperson said.
Consequently, the property was attached under the provisions of the NDPS Act. The attachment proceedings were conducted in the presence of the two independent witnesses, strictly in accordance with the prescribed legal procedures, he said.
As per the attachment order, the owner has been restrained from selling, leasing, transferring, altering, or creating any third-party interest in the property till further orders, the spokesperson added.

Sep 1: Royal Challengers Bangalore has named Australian leg-spinner Adam Zampa as a replacement for his compatriot Kane Richardson, who pulled out of the IPL starting September 19 in the UAE.